TWI501411B - Solar cell and module comprising the same - Google Patents

Description

Solar cell and its module

The invention relates to a battery and a battery module, in particular to a solar battery and a module thereof.

The solar spectrum contains visible light, ultraviolet light, infrared light and other wavelengths. Taking a twinned solar cell as an example, it mainly absorbs near-infrared light from visible light and some wavelength bands to achieve the purpose of converting light energy into electrical energy.

Among them, long-wavelength light (1100 nm or more) cannot be absorbed by the battery, or the efficiency of absorption and utilization is not good. Therefore, when the battery is exposed to light, most of the infrared light in the sunlight is not absorbed by the battery. However, the infrared light will increase the temperature of the battery through the battery. This temperature effect will affect the battery performance and stability, and reduce the photoelectric conversion efficiency. In addition, the battery illuminates the sunlight for a long time and receives the ultraviolet light therein, but the ultraviolet light is also a light that is difficult to be absorbed and utilized by the battery, and the ultraviolet light irradiation easily causes the film layer in the battery to decay, affects the quality of the film layer, and further reduces the battery. life. Therefore, the above light should be prevented from entering the battery to reduce the damage caused by the light.

Accordingly, it is an object of the present invention to provide a solar cell and a module thereof that can improve performance, operational stability, and conversion efficiency.

Therefore, the solar cell of the present invention comprises: a photoelectric conversion unit including a light-receiving first surface, and a plurality of light-transmissive first reflective films stacked on each other on the first surface of the photoelectric conversion unit, the plural First anti The film can reflect light that cannot be absorbed by the photoelectric conversion unit.

The solar cell module of the present invention comprises: a first plate that is transparent to light, a second plate disposed opposite the first plate, and a photoelectric conversion unit disposed between the first plate and the second plate, a package disposed between the first plate and the second plate, and a plurality of first reflective films that are transparent to light. The plurality of first reflective films are stacked on each other between the first plate and the photoelectric conversion unit, and reflect light that cannot be absorbed by the photoelectric conversion unit.

The effect of the invention is that: by arranging the plurality of first reflective films, light that cannot be absorbed by the battery is prevented from entering the photoelectric conversion unit, for example, the battery can be prevented from absorbing infrared light, and the problem that the infrared light causes the battery to overheat is prevented, thereby maintaining Battery efficiency and stability, improve conversion efficiency.

The above and other technical features, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. Before the present invention is described in detail, it is noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 1, a first preferred embodiment of the solar cell 1 of the present invention comprises: a photoelectric conversion unit 11, and a plurality of first reflective films 12 that are transparent to light.

The photoelectric conversion unit 11 includes a first face 111 that receives light, and a second face 112 that is opposite to the first face 111. In a single-sided light-emitting battery, the first surface 111 and the second surface 112 correspond to the front and back surfaces of the battery. Actually, the photoelectric conversion unit 11 includes a substrate, an emitter layer formed on a surface of the substrate and forming a pn junction with the substrate, and a film layer such as an anti-reflection layer (for example, SiN _x ). Since the specific structure and the number of layers of the photoelectric conversion unit 11 are not the improvement points of the present invention, the description will not be repeated, and the photoelectric conversion unit 11 is also illustrated in a single layer.

The plurality of first reflective films 12 are stacked on each other on the first surface 111 of the photoelectric conversion unit 11, and each of the first reflective films 12 includes at least two optical film layers 121 stacked on top of each other and having different refractive indices. The plurality of first reflection films 12 can reflect light that cannot be absorbed by the photoelectric conversion unit 11, and the optical characteristics of the plurality of first reflection films 12 are related to the wavelength of the light A that cannot be absorbed by the photoelectric conversion unit 11. The light A that cannot be absorbed by the photoelectric conversion unit 11 is light that cannot be absorbed by the battery and converted into electric energy. The optical characteristics of each of the first reflective films 12 of the present embodiment include the thickness and refractive index of the first reflective film 12. The wavelength of the light A that cannot be absorbed by the photoelectric conversion unit 11 is 280 nm to 400 nm and 1100 nm to 2500 nm, wherein the light A is, for example, ultraviolet light or infrared light, and the wavelength of the infrared light is about 1100 nm to 2500 nm, and the wavelength of the ultraviolet light is about 280nm~400nm.

The "thickness" as used herein refers to the physical thickness of the layer, and the product of the physical thickness and the refractive index is the "optical thickness". An optical film has different absorption rates for light of different wavelengths, and optical characteristics of the optical film include optical thickness, and therefore optical characteristics of the plurality of first reflection films 12 of the present invention and light rays A that cannot be absorbed by the photoelectric conversion unit 11 Wavelength related.

The present invention is mainly provided by the plurality of first reflective films 12 disposed on the first surface 111 of the photoelectric conversion unit 11 that receives light, and the respective layers of the first reflective film 12 are transmitted through a suitable thickness and refractive index. Light A produces a better reflectivity, so that light A that is directed from the outside toward the first face 111 It is reflected at the first time to prevent the light A that cannot be absorbed and utilized by the battery from entering the photoelectric conversion unit 11. Specifically, the plurality of first reflective films 12 can reflect infrared light and ultraviolet light, thereby preventing the infrared light from being absorbed, preventing the infrared light from causing the battery to overheat, thereby enabling the battery to operate normally, having good performance and stability, and Improve conversion efficiency. It also prevents UV light from being absorbed and reduces UV light to extend battery life. It should be noted that the plurality of first reflective films 12 have an appropriate film thickness and refractive index, and the effect on the absorption of visible light by the battery is very slight.

The reflective structure formed by the plurality of first reflective films 12 may be, but not limited to, the following three forms:

(1) Each of the first reflective films 12 includes two optical film layers 121 having different refractive indices, wherein a layer having a higher refractive index is represented by H, and a layer having a lower refractive index is represented by L, the plural number A low refractive index layer must be further disposed on a reflective film 12 such that a multilayer film reflective structure of (L/H) _n /L is integrally formed, where n is the number of film layers and is an integer greater than or equal to 2. For example, when n=2, it represents a total of five optical film layers, and the five optical film layers form a stacking method with a refractive index of (L/H/L/H)/L, wherein the outer layer is outside the brackets. The refractive index layer L represents the film layer closest to the outer side.

(2) The plurality of first reflection films 12 collectively form (L/2+H+L/2) _p +(L'/2+H'+L'/2) _q , wherein p and q are film layers The number of all is an integer greater than or equal to 1, and the refractive index of the L layer is not equal to the refractive index of the L' layer, and the refractive index of the H layer is not equal to the refractive index of the H' layer. Since each of the high-emissivity layers of the present form is stacked with a low refractive index layer, wherein L/2 or L'/2 means that the film thickness of the low refractive index layer of the present form is only the first form. The film thickness of the low-luminosity layer is half.

(3) The plurality of first reflection films 12 collectively form L/2+W(LJ2HJL) _a +X(LMHML) _b +Y(L/2+H+L/2)+(L/2+H+L/ 2) _c + Z(L/2+H+L/2), where a, b, and c are the number of film groups, all being integers greater than or equal to 0, but not equal to 0 at the same time. Wherein H and L respectively represent the highest and lowest refractive index layers, and J, H, and M represent a layer with a refractive index between H and L, and J≠H≠M. W, X, Y, and Z are variables in the building-block approach. The range of each variable is 0~2, but W, X, Y, and Z are not equal to 0 at the same time.

Referring to Figure 2, the penetration spectrum of the third type of reflective film shows that the light transmittance corresponds to the wavelength of the incident light. The source is the article "THE OPTICAL SOCIETY OF AMERICA", VOLUME 53 (November 1963) "Multilayer Filters with Wide Transmittance Bands". It can be seen from the figure that the reflective film of this design has a very low transmittance for ultraviolet light (wavelength of less than about 400 nm), indicating that the reflective film has a high reflectance in the ultraviolet light band. In addition, the transmittance of near-infrared light having a wavelength of 1200 nm to 1400 nm is also low, indicating that the reflectance is high in this band. The reflective film also has a certain reflectance for infrared light having a wavelength of 1400 nm or more. Although the reflectance of the local band is low, the effect of reflecting infrared light as a whole is good.

Referring to FIG. 1, each of the first reflective films 12 of the present invention may have the same structure, or may be slightly adjusted according to the reflection requirement, so that the structure between the plurality of first reflective films 12 has difference. At least some of the first reflective films 12 of the plurality of first reflective films 12 may include Several particles ranging in size from 1 nm to 30 nm. Specifically, each of the optical film layers 121 in the first reflective film 12 can be formed by using, but not limited to, a spray method, such as an Ultra Sonic Sprayer method, when the optical film layer 121 is sprayed, The optical film layer 121 is cured by preliminary baking at a temperature of about 150 ° C and heating at a temperature of 400 ° C.

The liquid film 121 liquid solvent such as isopropyl alcohol (IPA), the optical film layer 121 liquid solute contains nano particles having a size of 1 nm to 30 nm, the nano particles such as SiO ₂ , TiO ₂ , and different sizes or materials are selected. The nanoparticles can make the refractive index of the optical film layer 121 different. IPA for example using the same solvent in which the particle size of 13nm blending of TiO ₂ available optical film refractive index of about 2.3 to 121; blending of TiO ₂ particle diameter of 20nm can be obtained an optical refractive index of about 1.9 The film layer 121; and the refractive index of the SiO ₂ optical film layer 121 is generally smaller than the refractive index of the TiO ₂ optical film layer 121.

For example, the specific structure of each of the first reflective films 12 may include three optical film layers 121, which are sequentially a TiO ₂ layer having a thickness of about 57 nm and a refractive index of about 2.3, and a thickness of about 95 nm. SiO ₂ layer and a refractive index of about 1.38, and a thickness of about 69nm and a refractive index of about 1.9 of the SiO ₂ layer. Among them, the thickness of the three layers is mainly obtained by spraying, drying and solidifying the smaller-sized TiO ₂ and SiO ₂ nanoparticles.

The battery of this embodiment actually further includes an electrode unit not shown, the electrode unit including a first surface 111 that passes through the plurality of first reflective films 12 and the anti-reflection layer to contact the photoelectric conversion unit 11 The first electrode (ie, the front electrode) and a second electrode (ie, the back electrode) that contacts the second face 112 of the photoelectric conversion unit 11. The first electrode and the second electrode cooperate with the battery The generated electrical energy is transmitted to the outside. However, since the electrode unit is not an improvement point of the present invention, it will not be described.

The solar cell 1 of the first preferred embodiment described above can be combined with other components to form a solar cell module, as explained below.

Referring to FIG. 3, a first preferred embodiment of the solar cell module of the present invention comprises: a first plate 2 and a second plate 3, a package 4, and a solar cell 1 as described above.

The first plate 2 and the second plate 3 are not particularly limited in implementation, and a glass or plastic plate can be used, and the plate on one side of the light receiving surface of the battery must be transparent. The first plate 2 of the embodiment is Light transmissive.

The encapsulant 4 is disposed between the first plate 2 and the second plate 3 and is in contact with the solar cell 1 . The material of the encapsulant 4 is, for example, a translucent ethylene vinyl acetate copolymer (EVA). Of course, other materials suitable for packaging may be used. In the module packaging process, the package material 4 is formed by heating and melting two EVA films respectively disposed above and below the solar cell 1 , so that the package material 4 includes a solar cell 1 The upper first package portion 41 and a second package portion 42 located below the solar cell 1.

The solar cell 1 in the battery module of the embodiment is a battery as shown in FIG. 1 , and thus includes a photoelectric conversion unit 11 disposed between the first plate 2 and the second plate 3 , and a plurality of transparent cells The first reflective film 12 of light. For convenience of illustration, each of the first reflective films 12 in the module draws only a single layer, but in practice each of the first reflective films 12 has a structure including at least two optical film layers as described above. The plurality of first reflective films 12 of the embodiment are located in the light Between the electrical conversion unit 11 and the first encapsulation portion 41 of the encapsulant 4, by arranging the plurality of first reflective films 12, the battery and other component packages are combined into a module, and the light that cannot be absorbed can also be reflected. A. However, the position of the plurality of first reflection films 12 is not limited to the embodiment, and will be described below by way of another embodiment.

Referring to FIG. 4, the second preferred embodiment of the solar cell module of the present invention is substantially the same as the module of the first preferred embodiment. The difference is that the solar cell 1 of the present embodiment mainly includes a photoelectric conversion unit 11 The plurality of first reflective films 12 of the present embodiment are formed on the surface of the first plate 2 facing the package 4, that is, the plurality of first reflective films 12 are located in the first package portion 41 of the package 4 and Between the first sheets 2 . The plurality of first reflective films 12 are formed on the inner side surface of the first plate 2 by spraying, and the first plate 2, the second plate 3, and the solar cell 1 are combined with the package 4.

It can be seen from the above two embodiments that the position of the plurality of first reflective films 12 in the module can be disposed between the first plate 2 and the photoelectric conversion unit 11, that is, the light received by the battery or the module. On the one hand, the infrared light and the ultraviolet light in the sunlight are reflected off, thereby avoiding overheating of the battery and the module, and prolonging the service life of the battery and the module. Of course, the plurality of first reflective films 12 may be formed on the outer side surface of the first plate material 2, that is, the surface contacting the outside world, and the need to reflect infrared light and ultraviolet light in sunlight may also be achieved.

In addition, the plurality of first reflective films 12 may be disposed between the second surface 112 of the photoelectric conversion unit 11 and the second package portion 42 or may be disposed on The second encapsulation portion 42 is between the second plate member 3.

Referring to FIG. 5, the third preferred embodiment of the solar cell module of the present invention is substantially the same as the module of the first preferred embodiment. The following mainly describes different places. Both the first plate 2 and the second plate 3 of the embodiment must be permeable to light. The solar cell 1 is a bi-facial solar cell, and includes a plurality of light transmissive units 11 and a plurality of transparent light transmissive first reflective films 12 The second reflective film 13.

The photoelectric conversion unit 11 includes an opposite first surface 111 and a second surface 112. Both the first surface 111 and the second surface 112 can receive light.

The plurality of second reflective films 13 are stacked on each other on the second surface 112 of the photoelectric conversion unit 11, and each of the second reflective films 13 includes at least two optical film layers stacked one on top of the other. The structure, the number of layers, the material, the manufacturing method, and the function of the plurality of second reflective films 13 are substantially the same as those of the plurality of first reflective films 12, so that the plurality of second reflective films 13 can also be reflected by the photoelectric conversion unit. 11 absorbed light A. The optical characteristics of the plurality of second reflection films 13 are related to the wavelength of the light A that cannot be absorbed by the photoelectric conversion unit 11, and the optical characteristics of each of the second reflection films 13 include the thickness and refractive index of the second reflection film 13. At least some of the plurality of second reflective films 13 may include a plurality of materials having a size of 1 nm to 30 nm.

Since the second surface 112 of the battery of the embodiment can also receive light, the plurality of second reflective films 13 are additionally disposed, and the infrared light and the ultraviolet light in the light incident from the side of the second surface 112 can be reflected outward. To avoid the problem of overheating caused by the battery absorbing infrared light, and to avoid the absorption of ultraviolet light, Less UV exposure to extend battery life.

The plurality of first reflective films 12 of the present embodiment are located between the first surface 111 of the photoelectric conversion unit 11 and the first package portion 41 of the package 4, and the plurality of second reflective films 13 are located at the photoelectric conversion unit 11. The second surface 112 is between the second encapsulation portion 42 of the encapsulant 4 . However, the implementation is not limited to this, and the following is explained by another embodiment.

Referring to FIG. 6, a fourth preferred embodiment of the solar cell module of the present invention is substantially the same as the module of the third preferred embodiment. The following mainly describes different places.

The battery of this embodiment mainly includes a photoelectric conversion unit 11 . The plurality of first reflective films 12 of the embodiment are formed on a surface of the first plate 2 facing the package 4 , and the plurality of first reflective films 12 are located in the package. The first encapsulation portion 41 of the material 4 is between the first plate member 2. The plurality of second reflective films 13 are formed on a surface of the second plate 3 facing the package 4 , and the plurality of second reflective films 13 are located between the second package portion 42 of the package 4 and the second plate 3 . . The plurality of first reflective films 12 and the plurality of second reflective films 13 are formed on the inner side surfaces of the first plate 2 and the second plate 3 by spraying, and the first plate 2 and the second plate 3 are further The solar cell 1 is combined with the packaging material 4.

Of course, the position of the plurality of first reflective films 12 and the plurality of second reflective films 13 may be matched. For example, the plurality of first reflective films 12 are located on the first surface 111 of the photoelectric conversion unit 11 and the package 4 The plurality of second reflective films 13 are located between the second package portion 42 of the package 4 and the second plate member 3 between the first package portions 41. Or the plurality of first reflective films 12 is located between the first encapsulation portion 41 of the package material 4 and the first plate member 2 , and the plurality of second reflection films 13 are located on the second surface 112 of the photoelectric conversion unit 11 and the second encapsulation portion 42 of the package material 4 . between.

Further, in the double-sided light-emitting battery module, it is absolutely unnecessary to provide the plurality of first reflection films 12 and the plurality of second reflection films 13 at the same time. It is possible to provide only the plural first reflection film 12 or only the plural second reflection film 13.

However, the above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, that is, the simple equivalent changes and modifications made by Daxun in accordance with the scope of the present invention and the description of the invention. All remain within the scope of the invention patent.

1‧‧‧Solar battery

11‧‧‧ photoelectric conversion unit

111‧‧‧ first side

112‧‧‧ second side

12‧‧‧First reflective film

121‧‧‧Optical film layer

13‧‧‧second reflective film

2‧‧‧ first plate

3‧‧‧Second plate

4‧‧‧Package

41‧‧‧First Packaging Department

42‧‧‧Second encapsulation

A‧‧‧Light

1 is a partial schematic view of a first preferred embodiment of a solar cell of the present invention; and FIG. 2 is a relationship diagram of light transmittance corresponding to the wavelength of incident light, showing a penetration spectrum of a reflective film applicable to the present invention; 3 is a partial cross-sectional view showing a first preferred embodiment of a solar cell module of the present invention; and FIG. 4 is a partial cross-sectional view showing a second preferred embodiment of the solar cell module of the present invention; A partial cross-sectional view of a third preferred embodiment of the solar cell module of the present invention; and FIG. 6 is a partial cross-sectional view showing a fourth preferred embodiment of the solar cell module of the present invention.

1‧‧‧Solar battery

11‧‧‧ photoelectric conversion unit

111‧‧‧ first side

112‧‧‧ second side

12‧‧‧First reflective film

121‧‧‧Optical film layer

A‧‧‧Light

Claims (8)

A solar cell comprising: a photoelectric conversion unit including a first surface that receives light; and a plurality of first reflective films that are permeable to light and stacked on each other at the first of the photoelectric conversion units a surface of the plurality of first reflective films having a reflectance greater than a transmittance of light having a wavelength of 1200 nm to 1400 nm or a wavelength of 280 nm to 400 nm; wherein at least some of the plurality of first reflective films comprise a plurality of dimensions Particles from 1 nm to 30 nm. The solar cell of claim 1, wherein the optical properties of the plurality of first reflective films are related to the wavelength of the light. The solar cell according to claim 2, wherein the optical characteristics of each of the first reflective films comprise a thickness and a refractive index of each of the first reflective films. The solar cell according to claim 1, wherein the particles are selected from the group consisting of SiO ₂ and TiO ₂ particles. A solar cell module comprising: a first plate that is transparent; a second plate disposed opposite the first plate; and a photoelectric conversion unit disposed between the first plate and the second plate; a plurality of first reflective films, the plurality of first reflective films being permeable to light and stacked on each other between the first plate and the photoelectric conversion unit, the plurality of first reflective films having a wavelength of 1200 nm to 1400 nm or a wavelength of The reflectance of the light of 280 nm to 400 nm is greater than the transmittance; wherein at least some of the plurality of first reflective films comprise a plurality of particles having a size of 1 nm to 30 nm. The solar cell module of claim 5, wherein the optical properties of the plurality of first reflective films are related to the wavelength of the light. The solar cell module of claim 6, wherein the optical properties of each of the first reflective films comprise a thickness and a refractive index of each of the first reflective films. The solar cell module according to claim 5, wherein the particles are selected from the group consisting of SiO ₂ and TiO ₂ particles.